Slicing, Dicing and Biopsying the Benign Histiocytoma

Patty Khuly, DVM
Published: April 06, 2011
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Two of my last four dogs have suffered from unsightly and technically benign skin tumors we call histiocytomas. Though histiocytomas typically resolve after two to three months (or less), the uncertainty of this tumor’s provenance leads most vets to slice it off (or at least part of it) so that everyone can sleep peacefully at night knowing no evil lurks untreated.

A surgical excision of a "benign" mass may sound extreme to you, but since histiocytomas can be both annoying and scary, the average veterinarian’s safety principle holds that the snip-snip is almost always the way to go.

Why annoying? Because they often show up on the head and feet, places where a perfectly round, ulcerated mass can be scratched or licked with wild abandon.

Why scary? Because it’s hard to tell if what’s just popped up on your dog’s skin (and it usually happens fast) is a nasty mast cell tumor (or some other such monster mass), or its more easy-going cousin, the histiocytoma.

While young dogs (under three years of age) are more likely to get these, they can happen to dogs of any age. Indeed, my late Frenchie, Sophie Sue, got one when she was already nine years old. Vincent had three before he was two years old.

Some breeds are more predisposed. Labrador retrievers and boxers, for example, make the short list. Though Frenchies aren’t mentioned, perhaps they should be. (Perhaps they should be on the list for almost everything, if my personal experience with Frenchies is any guide.)

Ugly and prominently placed as they typically are, most owners want histiocytomas removed. Some vets, however, will counsel owners to either wait a few weeks (especially if the dog is young and statistically less likely to be suffering from a malignant mass) or to have either a simple section of it snipped or a small tubular sample extracted (with a local anesthetic) for histopathological analysis at the lab.

Other vets will sometimes take a needle poke at it, though you should know that most pathologists find that histiocytomas are not easily diagnosed definitively through this method (via cytology).

If the dog is older or the mass is especially annoying to the dog or owner, however, we remove the whole sucker and clean up the mess quickly. Unfortunately, this approach is more costly and usually requires general anesthesia. It’s nonetheless the approach I take for more than half of these tumors. Better to be safe than sorry, right?

Still, most owners need to know they have a choice. The nervous Nellies among you (like me) are less likely to want to stare at a mass for a couple of months to see if it simply goes away. The rational or more anesthetically cautious, however, are justified in waiting — as long as their dog is young and/or hasn’t suffered from malignant masses in the past.

Whatever choice you make, consider histiocytomas an excellent foray into the world of skin tumors. It’s like a warm-up for what’s likely to come as your dog ages. And it’s not all bad. Look on the bright side: curing cancer is sometimes just a scalpel slice away.

Dr. Patty Khuly

Pic of the day: Benignancy by Dr. Khuly